Electrostatic air filtration systems of the charged media type are well known. Traditionally, these systems comprise a metallic screen charged with a high voltage/low amperage current which is sandwiched between a pair of fibrous filter pads and a pair of grounded metallic screens that cover each side of the filter sandwich. U.S. Pat. No. 4,549,887 and Canadian Pat. No. 1,175,754 describe charged media type air filters constructed in this fashion. Although these electrostatic air filters are much more efficient than passive air filtration systems, they have a feature in their design which can impair their efficiency. The close contact of the filter's charging screens with the fibrous filter pads can lead to a considerable voltage drop on the high voltage screen due to conduction across the filter media. This is especially true after the filter media has become soiled with dust and other airborne filtrates. A voltage drop of up to 60% of the input voltage has been observed on the charged screens of these filters. This voltage drop affects the strength of the electrostatic field created within the fibrous filter pads and thereby impairs the efficiency of the filter. The present invention overcomes this problem with a novel filter construction wherein contact between the fibrous filter media and at least one of the filter's charging screens is minimized or completely eliminated, enabling the maintenance of an electrostatic field of full or near full potential regardless of the contamination level of the filter media, thus providing an air filtration system of the charged media type which is dramatically more efficient than those of the prior art. It has also been established that an efficient filter can be produced with only two charging screens and a single filter pad, providing a more economical filter construction.